[FFmpeg-user] Poor quality output when converting avi to mp4

Ute Willmore uwillmore at remotegeo.com
Mon Jul 24 22:40:02 EEST 2017


I am still very new to video conversion and ffmpeg, so I don't understand
parts of your reply. Please explain:

What is non-standard about my input video?

I ran many conversion commands, and listed several of them in my original
message. Which one did you use?

What does "Muxing to TS" mean and why/how did you do that? What does
"Invalid NAL warnings mean?

I gather mp4box is another tool to use when dealing with videos and there
are all kinds of version available.

Is this the one you are using?

I think you are saying that no matter what I will have to use MP4Box or
something similar to make a "standard" avi video and then convert that new
video to mp4 using the ffmpeg command you used. Is that correct?

Obviously, I would prefer not to process the video twice, because the real
video can be quite large. Do you have any idea what needs to be done to
produce a standard avi video in the first place?



On Mon, Jul 24, 2017 at 12:55 PM, Gyan <gyandoshi at gmail.com> wrote:

> On Mon, Jul 24, 2017 at 11:56 PM, Ute Willmore <uwillmore at remotegeo.com>
> wrote:
> > Hi everyone,
> >
> > I am hoping someone on this list can help me with a problem I am having
> > when converting a .avi video to .mp4 using FFmpeg. The output I get
> starts
> > out looking good, but then degrades and by the time the 18 second video
> > finishes it is hard to recognize what's on the screen. The colors are all
> > off, some areas are just single color blobs where there used to be trees.
> >
> Running your conversion command on your source, I see
> Input stream #0:0 (video): 856 packets read (18695093 bytes); 104 frames
> decoded;
> Muxing to TS and playing that throws invalid NAL warnings.
> So I ran
> mp4box -aviraw video hd.avi
> which produced hd_video.h264. This plays fine with ffplay.
> Running
> ffmpeg  -v verbose -i hd_video.h264 -i hd.avi -map 0 -map 1:a -vf
> scale=640:480 out.mp4
> produces an undistorted output.
> As best as I can tell, ffmpeg does have issues with parsing non-standard
> H.264 bitstreams. It's certainly not as resilient as other decoders.
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